Transducers convert signals from one domain to another and are often used as sensors. One common transducer used as a sensor and seen in everyday life is a microphone, which converts sound waves to electrical signals. Another example of a common sensor is a thermometer. Various transducers exist that serve as thermometers by transducing temperature signals into electrical signals.
Microelectromechanical systems (MEMS) based sensors include a family of transducers produced using micromachining techniques. MEMS, such as a MEMS microphone, gather information from the environment by measuring the change of physical state in the transducer and transferring a transduced signal to processing electronics that are connected to the MEMS sensor. MEMS devices may be manufactured using micromachining fabrication techniques similar to those used for integrated circuits.
MEMS devices may be designed to function as, for example, oscillators, resonators, accelerometers, gyroscopes, thermometers, pressure sensors, microphones, microspeakers, and micro-mirrors. As an example, many MEMS devices use capacitive sensing techniques for transducing the physical phenomenon into electrical signals. In such applications, the capacitance change in the sensor is converted into a voltage signal using interface circuits.
One such capacitive sensing device is a MEMS microphone. A MEMS microphone generally has a deflectable membrane separated by a small distance from a rigid backplate. In response to a sound pressure wave incident on the membrane, it deflects towards or away from the backplate, thereby changing the separation distance between the membrane and backplate. Generally, the membrane and backplate are made out of conductive materials and form “plates” of a capacitor. Thus, as the distance separating the membrane and backplate changes in response to the incident sound wave, the capacitance changes between the “plate” and an electrical signal is generated.
MEMS, such as capacitive MEMS for example, are often used in mobile electronics, such as tablet computers or mobile phones. In some applications, it may be desirable to provide sensors with new or increased functionality in order to provide additional or improved functionality to the electronic system, such as a tablet computer or mobile phone, for example.